path: root/outrdf2.c

/* outrdf2.c	output routines for the Netwide Assembler to produce
 *		RDOFF version 2 format object files (which are intended
 *		mainly for use in proprietary projects, as the code to 
 *		load and execute them is very simple). They will also be 
 *		used for device drivers and possibly some executable files
 *		in the MOSCOW operating system. See Rdoff.txt for
 *		details.
 *
 * The Netwide Assembler is copyright (C) 1996-1998 Simon Tatham and
 * Julian Hall. All rights reserved. The software is
 * redistributable under the licence given in the file "Licence"
 * distributed in the NASM archive.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>

#include "nasm.h"
#include "nasmlib.h"
#include "outform.h"

/* VERBOSE_WARNINGS: define this to add some extra warnings... */
#define VERBOSE_WARNINGS     

#ifdef OF_RDF2

#define RDF_MAXSEGS 64	/* maximum number of segments - user configurable */

typedef unsigned short int16;
typedef unsigned char byte;

static const char *RDOFF2Id = "RDOFF2";	/* written to start of RDOFF files */


/* the records that can be found in the RDOFF header */

/* Note that whenever a segment is referred to in the RDOFF file, its number
 * is always half of the segment number that NASM uses to refer to it; this
 * is because NASM only allocates even numbered segments, so as to not
 * waste any of the 16 bits of segment number written to the file - this
 * allows up to 65533 external labels to be defined; otherwise it would be
 * 32764. */

struct RelocRec {
  byte	type;		/* must be 1, or 6 for segment base ref */
  byte	reclen;		/* set to 8 */
  byte	segment;	/* only 0 for code, or 1 for data supported,
			 * but add 64 for relative refs (ie do not require
			 * reloc @ loadtime, only linkage) */
  long	offset;		/* from start of segment in which reference is loc'd */
  byte	length;		/* 1 2 or 4 bytes */
  int16	refseg;		/* segment to which reference refers to */
};

struct ImportRec {
  byte 	type;		/* must be 2, or 7 for FAR import */
  byte	reclen;		/* equals 3+label length */
  int16	segment;	/* segment number allocated to the label for reloc
			 * records - label is assumed to be at offset zero
			 * in this segment, so linker must fix up with offset
			 * of segment and of offset within segment */
  char	label[33];	/* zero terminated... should be written to file until
			 * the zero, but not after it - max len = 32 chars */
};

struct ExportRec {
  byte	type;		/* must be 3 */
  byte  reclen;		/* equals 6+label length */
  byte	segment;	/* segment referred to (0/1) */
  long	offset;		/* offset within segment */
  char	label[33];	/* zero terminated as above. max len = 32 chars */
};

struct DLLRec {
  byte	type;		/* must be 4 */
  byte  reclen;		/* equals 1+library name */
  char	libname[128];	/* name of library to link with at load time */
};

struct BSSRec {
  byte	type;		/* must be 5 */
  byte  reclen;		/* equeals 4 */
  long	amount;		/* number of bytes BSS to reserve */
};

#define COUNT_SEGTYPES 9

static char * segmenttypes[COUNT_SEGTYPES] = {
  "null", "text", "code", "data", "comment", "lcomment", "pcomment",
  "symdebug", "linedebug" 
};

static int segmenttypenumbers[COUNT_SEGTYPES] = {
  0, 1, 1, 2, 3, 4, 5, 6, 7
};

/* code for managing buffers needed to seperate code and data into individual
 * sections until they are ready to be written to the file.
 * We'd better hope that it all fits in memory else we're buggered... */

#define BUF_BLOCK_LEN 4088		/* selected to match page size (4096)
                                         * on 80x86 machines for efficiency */

/***********************************************************************
 * Actual code to deal with RDOFF2 ouput format begins here...
 */

/* global variables set during the initialisation phase */

static struct SAA *seg[RDF_MAXSEGS];	/* seg 0 = code, seg 1 = data */
static struct SAA *header;	/* relocation/import/export records */

static FILE *ofile;

static efunc error;

static struct seginfo {
  char *segname;
  int   segnumber;
  int16 segtype;
  int16 segreserved;
  long  seglength;
} segments[RDF_MAXSEGS];

static int nsegments;

static long bsslength;
static long headerlength;

static void rdf2_init(FILE *fp, efunc errfunc, ldfunc ldef, evalfunc eval)
{
  int segtext, segdata, segbss;

  /* set up the initial segments */
  segments[0].segname = ".text"; 
  segments[0].segnumber = 0;
  segments[0].segtype = 1;
  segments[0].segreserved = 0;
  segments[0].seglength = 0;

  segments[1].segname = ".data";
  segments[1].segnumber = 1;
  segments[1].segtype = 2;
  segments[1].segreserved = 0;
  segments[1].seglength = 0;

  segments[2].segname = ".bss";
  segments[2].segnumber = 2;
  segments[2].segtype = 0xFFFF;	/* reserved - should never be produced */
  segments[2].segreserved = 0;
  segments[2].seglength = 0;

  nsegments = 3;

  ofile = fp;
  error = errfunc;

  seg[0] = saa_init(1L);
  seg[1] = saa_init(1L);
  seg[2] = NULL;		/* special case! */

  header = saa_init(1L);

  segtext = seg_alloc();
  segdata = seg_alloc();
  segbss = seg_alloc();
  if (segtext != 0 || segdata != 2 || segbss != 4)
    error(ERR_PANIC,"rdf segment numbers not allocated as expected (%d,%d,%d)",
	  segtext,segdata,segbss);
  bsslength=0;
  headerlength = 0;
}

static long rdf2_section_names(char *name, int pass, int *bits)
{
  int 	i;
  char 	* p, * q;
  int	code = -1;
  int 	reserved = 0;

  /*
   * Default is 32 bits, in the text segment.
   */
  if (!name) {
    *bits = 32;
    return 0;
  }

  /* look for segment type code following segment name */
  p = name;
  while (*p && !isspace(*p)) p++;
  if (*p) {	/* we're now in whitespace */
    *p++ = '\0';
    while (*p && isspace(80)) *p++ = '\0';
  }
  if (*p) {	/* we're now in an attribute value */
    /*
     * see if we have an optional ',number' following the type code
     */
    if ((q = strchr(p, ','))) {
      *q++ = '\0';

      reserved = readnum(q, &i);
      if (i) {
	  error(ERR_NONFATAL, "value following comma must be numeric");
	  reserved = 0;
      }
    }
    /*
     * check it against the text strings in segmenttypes 
     */

    for (i = 0; i < COUNT_SEGTYPES; i++)
      if (!nasm_stricmp(p, segmenttypes[i])) {
	code = segmenttypenumbers[i];
	break;
      }
    if (code == -1) {	/* didn't find anything */
      code = readnum(p, &i);
      if (i) {
	error(ERR_NONFATAL, "unrecognised RDF segment type (%s)",p);
	code = 3;
      }
    }
  }    
  for (i = 0; i < nsegments; i++) {
    if (!strcmp(name, segments[i].segname)) {
      if (code != -1 || reserved != 0) 
	error(ERR_NONFATAL, "segment attributes specified on"
	      " redeclaration of segment");
      return segments[i].segnumber * 2;
    }
  }

  /* declaring a new segment! */

  if (code == -1) {
    error(ERR_NONFATAL, "new segment declared without type code");
    code = 3;
  }
  if (nsegments == RDF_MAXSEGS) {
    error(ERR_FATAL, "reached compiled-in maximum segment limit (%d)",
	  RDF_MAXSEGS);
    return NO_SEG;
  }

  segments[nsegments].segname = nasm_strdup(name);
  i = seg_alloc();
  if (i % 2 != 0)
    error(ERR_PANIC, "seg_alloc() returned odd number");
  segments[nsegments].segnumber = i >> 1;
  segments[nsegments].segtype = code;
  segments[nsegments].segreserved = reserved;
  segments[nsegments].seglength = 0;

  seg[nsegments] = saa_init(1L);

  return i;
}

static void write_reloc_rec(struct RelocRec *r)
{
  char buf[4],*b;

  if (r->refseg != (int16)NO_SEG && (r->refseg & 1)) /* segment base ref */
      r->type = 6;

  r->refseg >>= 1;    /* adjust segment nos to RDF rather than NASM */

  saa_wbytes(header,&r->type,1);
  saa_wbytes(header,&r->reclen,1);
  saa_wbytes(header,&r->segment,1);
  b = buf; WRITELONG(b,r->offset);
  saa_wbytes(header,buf,4);
  saa_wbytes(header,&r->length,1);
  b = buf; WRITESHORT(b,r->refseg);
  saa_wbytes(header,buf,2);
  headerlength += r->reclen + 2;
}

static void write_export_rec(struct ExportRec *r)
{
  char buf[4], *b;

  r->segment >>= 1;

  saa_wbytes(header,&r->type,1);
  saa_wbytes(header,&r->reclen,1);
  saa_wbytes(header,&r->segment,1);
  b = buf; WRITELONG(b,r->offset);
  saa_wbytes(header,buf,4);
  saa_wbytes(header,r->label,strlen(r->label) + 1);
  headerlength += r->reclen + 2;
}

static void write_import_rec(struct ImportRec *r)
{
  char buf[4], *b;

  r->segment >>= 1;

  saa_wbytes(header,&r->type,1);
  saa_wbytes(header,&r->reclen,1);
  b = buf; WRITESHORT(b,r->segment);
  saa_wbytes(header,buf,2);
  saa_wbytes(header,r->label,strlen(r->label) + 1);
  headerlength += r->reclen + 2;
}

static void write_bss_rec(struct BSSRec *r)
{
    char buf[4], *b;

    saa_wbytes(header,&r->type,1);
    saa_wbytes(header,&r->reclen,1);
    b = buf; WRITELONG(b,r->amount);
    saa_wbytes(header,buf,4);
    headerlength += r->reclen + 2;
}

static void write_dll_rec(struct DLLRec *r)
{
    saa_wbytes(header,&r->type,1);
    saa_wbytes(header,&r->reclen,1);
    saa_wbytes(header,r->libname,strlen(r->libname) + 1);
    headerlength += r->reclen + 2;
}

static void rdf2_deflabel(char *name, long segment, long offset,
			 int is_global, char *special)
{
  struct ExportRec r;
  struct ImportRec ri;
#ifdef VERBOSE_WARNINGS
  static int warned_common = 0;
#endif
  static int farsym = 0;
  static int i;

  if (special) {
    while(*special == ' ' || *special == '\t') special++;

    if (!nasm_stricmp(special, "far")) {
      farsym = 1;
    }
    else if (!nasm_stricmp(special, "near")) {
      farsym = 0;
    }
    else
      error(ERR_NONFATAL, "unrecognised symbol type `%s'", special);
  }

  if (name[0] == '.' && name[1] == '.' && name[2] != '@') {
    error (ERR_NONFATAL, "unrecognised special symbol `%s'", name);
    return;
  }

  if (is_global == 2) {
#ifdef VERBOSE_WARNINGS
    if (!warned_common) {
      error(ERR_WARNING,"common declarations not supported: using extern");
      warned_common = 1;
    }
#endif
    is_global = 1;
  }

  for (i = 0; i < nsegments; i++) {
    if (segments[i].segnumber == segment>>1) break;
  }
  if (i >= nsegments) {   /* EXTERN declaration */
    if (farsym)
      ri.type = 7;
    else
      ri.type = 2;
    ri.segment = segment;
    strncpy(ri.label,name,32);
    ri.label[32] = 0;
    ri.reclen = 3 + strlen(ri.label);
    write_import_rec(&ri);
  } else if (is_global) {
    r.type = 3;
    r.segment = segment;
    r.offset = offset;
    strncpy(r.label,name,32);
    r.label[32] = 0;
    r.reclen = 6 + strlen(r.label);
    write_export_rec(&r);
  }
}

static void membufwrite(int segment, void * data, int bytes)
{
  int i;
  char buf[4], * b;

  for (i = 0; i < nsegments; i++) {
    if (segments[i].segnumber == segment) break;
  }
  if (i == nsegments)
    error(ERR_PANIC, "can't find segment %d", segment);
  
  if (bytes < 0) {
    b = buf;
    if (bytes == -2)
      WRITESHORT(b,*(short *)data);
    else
      WRITELONG(b,*(long *)data);
    data = buf;
    bytes = -bytes;
  }
  segments[i].seglength += bytes;
  saa_wbytes(seg[i],data,bytes);
}

static int getsegmentlength(int segment)
{
  int i;
  for (i = 0; i < nsegments; i++) {
    if (segments[i].segnumber == segment) break;
  }
  if (i == nsegments)
    error(ERR_PANIC, "can't find segment %d", segment);

  return segments[i].seglength;
}
    
static void rdf2_out (long segto, void *data, unsigned long type,
		     long segment, long wrt)
{
  long bytes = type & OUT_SIZMASK;
  struct RelocRec rr;
  unsigned char databuf[4],*pd;
  int seg;

  if (segto == NO_SEG) {
      if ((type & OUT_TYPMASK) != OUT_RESERVE)
	  error (ERR_NONFATAL, "attempt to assemble code in ABSOLUTE space");
      return;
  }

  segto >>= 1;    /* convert NASM segment no to RDF number */

  for (seg = 0; seg < nsegments; seg++) {
    if (segments[seg].segnumber == segto) break;
  }
  if (seg >= nsegments) {
    error(ERR_NONFATAL,"specified segment not supported by rdf output format");
    return;
  }

  if (wrt != NO_SEG) {
    wrt = NO_SEG;		       /* continue to do _something_ */
    error (ERR_NONFATAL, "WRT not supported by rdf output format");
  }

  type &= OUT_TYPMASK;

  if (segto == 2 && type != OUT_RESERVE)
  {
      error(ERR_NONFATAL, "BSS segments may not be initialised");

      /* just reserve the space for now... */

      if (type == OUT_REL2ADR)
	bytes = 2;
      else
	bytes = 4;
      type = OUT_RESERVE;
  }

  if (type == OUT_RESERVE) {
      if (segto == 2)		/* BSS segment space reserverd */
	  bsslength += bytes;
      else
	while (bytes --)
	    membufwrite(segto,databuf,1);
  }
  else if (type == OUT_RAWDATA) {
      if (segment != NO_SEG)
	  error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");

      membufwrite(segto,data,bytes);
  }
  else if (type == OUT_ADDRESS) {

    /* if segment == NO_SEG then we are writing an address of an
       object within the same segment - do not produce reloc rec. */

    /* FIXME - is this behaviour sane? at first glance it doesn't
       appear to be. Must test this thoroughly...! */

    if (segment != NO_SEG)
    {
	/* it's an address, so we must write a relocation record */

	rr.type = 1;		/* type signature */
	rr.reclen = 8;
	rr.segment = segto;		/* segment we're currently in */
	rr.offset = getsegmentlength(segto);	/* current offset */
	rr.length = bytes;		/* length of reference */
	rr.refseg = segment;	/* segment referred to */
	write_reloc_rec(&rr);
    }

    pd = databuf;	/* convert address to little-endian */
    if (bytes == 2)
      WRITESHORT (pd, *(long *)data);
    else
      WRITELONG (pd, *(long *)data);

    membufwrite(segto,databuf,bytes);

  }
  else if (type == OUT_REL2ADR)
  {
    if (segment == segto)
      error(ERR_PANIC, "intra-segment OUT_REL2ADR");

    rr.reclen = 8;
    rr.offset = getsegmentlength(segto);	/* current offset */
    rr.length = 2;		/* length of reference */
    rr.refseg = segment;	/* segment referred to (will be >>1'd)*/

    if (segment != NO_SEG && segment % 2) {
      rr.type = 6;
      rr.segment = segto;	/* memory base refs *aren't ever* relative! */
      write_reloc_rec(&rr);

      /* what do we put in the code? Simply the data. This should almost
       * always be zero, unless someone's doing segment arithmetic...
       */
      rr.offset = *(long *) data;
    }
    else
    {
      rr.type = 1;		/* type signature */
      rr.segment = segto+64;	/* segment we're currently in + rel flag */
      write_reloc_rec(&rr);

      /* work out what to put in the code: offset of the end of this operand,
       * subtracted from any data specified, so that loader can just add
       * address of imported symbol onto it to get address relative to end of
       * instruction: import_address + data(offset) - end_of_instrn */

      rr.offset = *(long *)data -(rr.offset + bytes);
    }
    
    membufwrite(segto,&rr.offset,-2);
  }
  else if (type == OUT_REL4ADR)
  {
    if (segment == segto)
      error(ERR_PANIC, "intra-segment OUT_REL4ADR");
    if (segment != NO_SEG && segment % 2) {
      error(ERR_PANIC, "erm... 4 byte segment base ref?");
    }

    rr.type = 1;		/* type signature */
    rr.segment = segto+64;	/* segment we're currently in + rel tag */
    rr.offset = getsegmentlength(segto);	/* current offset */
    rr.length = 4;		/* length of reference */
    rr.refseg = segment;	/* segment referred to */
    rr.reclen = 8;
    write_reloc_rec(&rr);

    rr.offset = *(long *)data -(rr.offset + bytes);

    membufwrite(segto,&rr.offset,-4);
  }
}

static void rdf2_cleanup (int debuginfo) {
  long		l;
  struct BSSRec	bs;
  int		i;

    (void) debuginfo;

  /* should write imported & exported symbol declarations to header here */

  /* generate the output file... */
  fwrite(RDOFF2Id,6,1,ofile);	/* file type magic number */

  if (bsslength != 0)		/* reserve BSS */
  {
      bs.type = 5;
      bs.amount = bsslength;
      bs.reclen = 4;
      write_bss_rec(&bs);
  }

  /*
   * calculate overall length of the output object
   */
  l = headerlength + 4;
  
  for (i = 0; i < nsegments; i++) {
    if (i == 2) continue;	/* skip BSS segment */
    l += 10 + segments[i].seglength;
  }
  l += 10;	/* null segment */

  fwritelong(l, ofile);

  fwritelong(headerlength, ofile);
  saa_fpwrite(header,ofile);	/* dump header */
  saa_free(header);

  for (i = 0; i < nsegments; i++) {
    if (i == 2) continue;

    fwriteshort(segments[i].segtype, ofile);
    fwriteshort(segments[i].segnumber, ofile);
    fwriteshort(segments[i].segreserved, ofile);
    fwritelong(segments[i].seglength, ofile);

    saa_fpwrite(seg[i], ofile);
    saa_free(seg[i]);
  }

  /* null segment - write 10 bytes of zero */
  fwritelong(0,ofile);
  fwritelong(0,ofile);
  fwriteshort(0,ofile);

  fclose(ofile);
}

static long rdf2_segbase (long segment) {
    return segment;
}

static int rdf2_directive (char *directive, char *value, int pass) {
    struct DLLRec r;
    
    if (! strcmp(directive, "library")) {
	if (pass == 1) {
	    r.type = 4;
	    strcpy(r.libname, value);
	    write_dll_rec(&r);
	}
	return 1;
    }

    return 0;
}

static void rdf2_filename (char *inname, char *outname, efunc error) {
  standard_extension(inname,outname,".rdf",error);
}

static char *rdf2_stdmac[] = {
    "%define __SECT__ [section .text]",
    "%imacro library 1+.nolist",
    "[library %1]",
    "%endmacro",
    "%macro __NASM_CDecl__ 1",
    "%endmacro",
    NULL
};

static int rdf2_set_info(enum geninfo type, char **val)
{
    return 0;
}


struct ofmt of_rdf2 = {
  "Relocatable Dynamic Object File Format v2.0",
  "rdf",
  NULL,
  null_debug_arr,
  &null_debug_form,
  rdf2_stdmac,
  rdf2_init,
  rdf2_set_info,
  rdf2_out,
  rdf2_deflabel,
  rdf2_section_names,
  rdf2_segbase,
  rdf2_directive,
  rdf2_filename,
  rdf2_cleanup
};

#endif /* OF_RDF2 */